Kirby said if there were no attacks on US troops, there would be no need for retaliatory strikes.
The killing of an Iranian-backed militia leader in Iraq will likely galvanize Iran’s allies in the country to try to expel the US.
The attack has been linked to the retaliatory US airstrikes against Iranian-aligned groups and their positions.
Iraq has witnessed tit-for-tat attacks between hardline Iran-backed armed groups and US forces stationed there.
Biden can retaliate without effect on hostage deal, Washington says.
The Iranian policy with Kataib Hezbollah is similar to its policy with Hamas after the massive unprecedented attack on Israel on October 7.
Iranian-backed groups have also targeted US forces in Iraq and Syria over the last four years with dozens of attacks.
This hints that the IRGC is likely coordinating the attacks and "corralling" Iran's proxies which would normally argue over public leadership.
The group, which goes by the Islamic Resistance in Iraq, claimed 11 attacks against US forces on Friday, the most in a single day since they began in mid-October.
A ballistic missile attack that targeted Ain al-Assad caused one death, several non-serious injuries, and some minor damage to infrastructure.